3D shape measurement device

Abstract

To provide a three-dimensional shape measuring device capable of reducing measurement errors and performing accurate measurements in pinhole array scanning using a confocal optical system. A three-dimensional shape measurement device according to one embodiment of the present invention is a three-dimensional shape measurement device using a confocal optical system, and includes at least an aperture plate on which a plurality of confocal apertures through which light from a light source passes are arranged two-dimensionally at a predetermined arrangement period, and an aperture plate displacement unit that displaces the aperture plate at a uniform speed in a predetermined direction perpendicular to the optical axis direction so as to change the relative positional relationship between the position of the object-side focusing point and the position of the object to be measured in the direction perpendicular to the optical axis direction. The three-dimensional shape measurement device controls the movement speed of the aperture plate, the rotation speed of the rotor, and the exposure time and exposure timing of the photodetector group so that the exposure time of the photodetector group coincides with the time it takes for the aperture plate to move a distance obtained by multiplying the predetermined arrangement period by an integer n greater than or equal to 2.

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional shape measurement apparatus that measures the three-dimensional shape of an object using a confocal optical system. [Background technology]

[0002] One method for measuring three-dimensional shapes such as the surface shape of an object is to measure the surface shape of the object by acquiring height information for each point on the object's surface using a confocal optical system. In principle, measurements using a confocal optical system are performed in units of "points," so special ingenuity is required to measure planar areas.

[0003] A technique for measuring a surface area such as the surface of an object using this type of confocal optical system is disclosed in Japanese Patent Laid-Open Publication No. 9-329748 (Patent Document 1).

[0004] Patent Document 1 discloses a confocal microscope equipped with a light source and a Nipkow disk with multiple apertures. Each aperture functions as a point light source and a detector. The multiple light beams passing through each aperture are focused by an objective lens at corresponding focusing positions on the object to be measured. Therefore, by rotating the Nipkow disk, the light beams (hereinafter referred to as spots) that pass through the multiple apertures and are focused at multiple focusing positions on the object to be measured can be scanned easily and quickly on the surface of the object to be measured.

[0005] Furthermore, in the method of scanning a spot on the surface of a measurement object using a Nipkow disk, it is difficult to prevent adverse effects caused by the rotation of the Nipkow disk. One adverse effect of the rotation of the Nipkow disk is that the curvature of the curve traced by the trajectory of an aperture (i.e., a pinhole) as the Nipkow disk rotates varies depending on the distance from the center of the disk. Since the curvature of the trajectory differs for each aperture, variations occur, such as differences in the scanning speed for each aperture. Furthermore, vibrations caused by continuous rotation, including rotational wobble due to disk eccentricity, are unavoidable. To address these issues, Japanese Patent Laid-Open Publication No. 9-329748 (Patent Document 2) discloses a three-dimensional shape measurement device capable of linearly scanning multiple spots on the surface of a measurement object. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-329748 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-160612 Summary of the Invention [Problem to be solved by the invention]

[0007] In pinhole array scanning using a confocal optical system of a pinhole array-type 3D shape measurement device with multiple apertures in an aperture plate, the timing at which light passes through each pixel varies. Therefore, if the object to be measured moves due to vibration or other factors, the uniformity of the scan deteriorates. In addition, manufacturing aperture plates is difficult, and individual differences in the diameter of the apertures can occur. As a result, the uniformity of the scan also deteriorates, making accurate measurements difficult.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a three-dimensional shape measurement device that can perform accurate measurements in pinhole array scanning using a confocal optical system. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a three-dimensional shape measurement device according to one embodiment of the present invention is a three-dimensional shape measurement device using a confocal optical system, and includes an aperture plate on which a plurality of confocal apertures through which light from a light source passes are arranged two-dimensionally at a predetermined arrangement period; an objective lens that focuses each of the lights that have passed through the plurality of confocal apertures at an object-side focusing point and that refocuses the reflected light of this focused light by a measurement object at the corresponding confocal aperture; and a plurality of parallel plate-shaped members that are different from each other in at least one of refractive index and thickness along the optical axis of the objective lens. a rotating body disposed along a rotation direction so as to intersect with the optical axis; and a driving unit for continuously rotating the rotating body at a predetermined speed, wherein the focal position changing unit discretely changes the position of the object-side light-focusing point in the optical axis direction every time the parallel plate-shaped member intersecting with the optical axis changes with the rotation of the rotating body; a photodetector group having a plurality of photodetectors for outputting a signal according to the intensity of the reflected light that has passed through the confocal aperture again; and a focusing unit for rotating the aperture plate in a predetermined direction perpendicular to the optical axis direction so as to change the relative positional relationship between the position of the object-side light-focusing point and the position of the object to be measured in the direction perpendicular to the optical axis direction. an aperture plate displacement unit that displaces the aperture plate at a uniform speed; a group of photodetectors that is exposed a plurality of times during a period in which the aperture plate is displaced at a uniform speed in the predetermined direction perpendicular to the optical axis direction by the aperture plate displacement unit; each exposure of the group of photodetectors is performed for each period in which an imaging target area is included in the parallel plate-shaped member; and the moving speed of the aperture plate, the rotation speed of the rotor, and the exposure time and exposure timing of the group of photodetectors are controlled so that the exposure time of the group of photodetectors coincides with the time it takes for the aperture plate to move a distance obtained by multiplying the predetermined array period by an integer n of 2 or greater. a height determination unit that estimates, for each photodetector, a position in the optical axis direction of the measured object at which the intensity of the reflected light incident on the photodetector is maximized based on a signal from the photodetector for each position of the object-side focusing point that is discretely changed in the optical axis direction; a cover member that is provided on the aperture plate and displaced integrally with the aperture plate by the aperture plate displacement unit, and that has a transparent body that transmits light from the light source and irradiates the light onto the plurality of confocal apertures, and that protects the plurality of confocal apertures from dust; and the cover member is designed in consideration of the optical characteristics of the entire optical system including the transparent body,and an imaging optical system that guides the reflected light that has passed through the confocal aperture again to the photodetector. In the three-dimensional shape measuring device, it is preferable that the imaging control unit switches between control in which the exposure time of the photodetector group coincides with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by an integer n greater than or equal to 2, and control in which the exposure time of the photodetector group coincides with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by 1. Furthermore, in the three-dimensional shape measurement device, it is preferable that the imaging control unit matches the exposure time of the photodetector group with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by an integer n greater than or equal to 2, with the exposure time of the photodetector group with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by 1. [Effects of the Invention]

[0010] According to the three-dimensional shape measuring device of the present invention, it is possible to reduce measurement errors in pinhole array scanning using a confocal optical system and perform accurate measurements. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic overall view showing an example of the configuration of a three-dimensional shape measuring apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing an example of the configuration of an aperture plate that constitutes the three-dimensional shape measuring apparatus according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a plan view showing a first control example of the aperture plate constituting the three-dimensional shape measuring apparatus according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a plan view showing a second control example of the aperture plate constituting the three-dimensional shape measuring apparatus according to the first embodiment of the present invention. [Figure 5] 5A and 5B are diagrams for explaining a second control example of the aperture plate constituting the three-dimensional shape measuring apparatus according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a perspective view showing an example of the configuration of a focal position changing unit. [Figure 7]FIG. 1 is a block diagram schematically illustrating an example of the internal configuration of an image processing apparatus. [Figure 8] 2A is a side view of an aperture plate provided with a cover member according to the example shown in FIG. 1, and FIG. 2B is a perspective view thereof. [Figure 9] FIG. 10 is an explanatory diagram showing an example of a timing chart for obtaining a clear image. [Figure 10] FIG. 2 is a perspective view showing an example of the configuration of a reaction force mechanism. [Figure 11] FIG. 10 is a schematic overall view showing an example of the configuration of a three-dimensional shape measuring apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a three-dimensional shape measuring apparatus according to the present invention will be described with reference to the accompanying drawings.

[0013] A three-dimensional shape measurement device according to one embodiment of the present invention is a pinhole array (PHA) type three-dimensional shape measurement device. This three-dimensional shape measurement device measures the shape of a measurement object using a confocal optical system having a two-dimensionally arranged confocal aperture array. The confocal aperture array is arranged two-dimensionally on an aperture plate with a predetermined arrangement period. Examples of measurement objects include electrode terminals (e.g., tens to hundreds of microns in size) of mass-produced parts such as IC packages.

[0014] (First embodiment) 1 is a schematic overall view showing an example of the configuration of a three-dimensional shape measuring device according to a first embodiment of the present invention. In the following explanation, an example is shown in which the optical axis direction is the Z axis, and directions perpendicular to the optical axis direction are the X axis and the Y axis.

[0015] The three-dimensional shape measuring device 10 includes an illumination optical system 11 having a light source 11a, an aperture plate (pinhole array) 12 arranged so that its principal surface is perpendicular to the optical axis direction, an objective lens 13, a focal position changing unit 14, a stage 16 for placing a measurement object 15, a photodetector group 17 having a plurality of photodetectors 17a that receive reflected light from the measurement object 15, a stage driver 18 for moving the stage 16 in each of the X, Y, and Z directions, a support base 19 that supports the stage 16 and the stage driver 18, and an image processing device 20. The stage driver 18 includes a stage Z displacement unit 21 and a stage XY displacement unit 22.

[0016] The light source 11a may be, for example, a halogen lamp or a laser. The light emitted from the light source 11a becomes a planar illumination beam via an illumination lens 23. This light illuminates the aperture plate 12 via a polarizing beam splitter 24.

[0017] FIG. 2 is a plan view showing an example of the configuration of the aperture plate 12. The upper part of FIG. 2 is a plan view of the aperture plate 12, and the lower part is an enlarged plan view of a partial region W of the upper part. The aperture plate 12 has a plurality of confocal apertures (hereinafter referred to as apertures) 25 arranged two-dimensionally. The plurality of apertures 25 are arranged such that (1) with respect to a row of the plurality of apertures 25 along the X axis, adjacent rows of apertures 25 in the positive direction of the Y axis are regularly shifted in the positive direction of the X axis, and (2) with respect to a row of the plurality of apertures 25 along the X axis, rows spaced a predetermined distance Δd in the positive direction of the Y axis are not shifted in the X axis direction. In other words, the aperture plate 12 has a plurality of apertures 25 arranged two-dimensionally with a predetermined arrangement period Δd. The aperture plate 12 is driven by an aperture plate displacement unit 26 (shown in FIG. 1) to be displaced in the Y axis direction, which is one of predetermined directions perpendicular to the optical axis direction. In the following description, an example will be shown in which the predetermined distance Δd is the distance in the Y-axis direction, and the aperture plate 12 is displaced in the positive and negative directions in the Y-axis direction.

[0018] Generally, adjacent apertures 25 of aperture plate 12, which is a two-dimensional aperture array in which a plurality of apertures 25 are arranged two-dimensionally, need to be spaced a predetermined distance apart to reduce crosstalk between beams. For this reason, in a confocal optical system having a two-dimensional aperture array, this spacing limits the resolution in the in-plane direction perpendicular to the optical axis. Meanwhile, in recent years, two-dimensional image sensors using solid-state imaging elements have been developed with extremely high pixel counts (for example, 5000 x 5000).

[0019] Therefore, by linearly scanning the aperture plate 12 while exposing the photodetector group 17, one aperture 25 is made to correspond to a plurality of pixels.

[0020] 2, when the aperture plate 12 is displaced by a predetermined array period (periodic interval) Δd due to scanning of the aperture plate 12, the inside of the imaging target area 27 can be uniformly scanned once by the openings 25. In the lower part of FIG. 2, the virtual positions of the photodetectors (pixels) 17a that make up the photodetector group 17 are indicated by dashed lines as virtual photodetectors 17a'.

[0021] By controlling the exposure time of the photodetectors 17a so that it coincides with the time it takes for the aperture plate 12 to move a distance calculated by multiplying the array period Δd by a positive integer m, it is possible to make uniform the time during which each photodetector 17a is irradiated with light through the apertures 25. This control is performed by the image processing device 20.

[0022] Each of the openings 25 in the aperture plate 12 functions as a point light source. Light passing through each opening 25 is projected onto the measurement object 15 via the focal position changing unit 14 and focused by the objective lens 13 onto a spot (object-side focusing point) conjugate with the point light source. Each object-side focusing point is located on a plane (hereinafter referred to as the object-side focusing plane) perpendicular to the optical axis direction at a predetermined position in the Z-axis direction. Note that the objective lens 13 may be configured, for example, by a plurality of lenses and diaphragms to form a double-telecentric optical system.

[0023] The aperture plate displacement unit 26 displaces the aperture plate 12 in a direction perpendicular to the optical axis direction. However, if the aperture plate 12 does not move at a constant speed, random unevenness will occur in the image, and the shape measurement accuracy will deteriorate. Therefore, it is desirable that the aperture plate displacement unit 26 use a linear motor or voice coil motor that is capable of direct drive with high controllability and perform closed-loop control.

[0024] The stage Z displacement unit 21 is configured with a general driving device such as a stepping motor, servo motor, or piezoelectric motor, and displaces the stage 16 in the optical axis direction. The amount, direction, and timing of this displacement are controlled by the image processing device 20 via the Z-axis driver 30. The stage Z displacement unit 21 roughly displaces the stage 16 in the optical axis direction, for example, before the start of measurement.

[0025] As described above, if the exposure time of the photodetector 17a is controlled to coincide with the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by a positive integer m, the time for which light is irradiated onto each photodetector 17a through the apertures 25 can be made uniform. On the other hand, if the exposure time of the photodetector 17a is controlled to coincide with the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by 1 (m=1), the timing at which light passes through each pixel will differ. Therefore, if the object 15 to be measured moves due to vibration or other reasons, the scanning uniformity will be reduced. Furthermore, manufacturing the aperture plate 12 is difficult, and individual differences in the diameters of the multiple apertures 25 may occur. As a result, the scanning uniformity will be reduced, which may make accurate measurement difficult.

[0026] Therefore, by changing the control method of the aperture plate 12 shown in Fig. 2 and scanning multiple periods to acquire one image, it is possible to reduce measurement errors due to deviations in measurement timing and individual differences in the diameter of the aperture 25. Specifically, the image processing device 20 controls the exposure time of the photodetector 17a so that it coincides with the time it takes for the aperture plate 12 to move a distance calculated by multiplying the array period Δd by an integer n, which is a positive integer m and is 2 or greater. The value of n is determined according to the diameter of the aperture 25.

[0027] 3 and 4 are diagrams for explaining a method of controlling the aperture plate 12. Fig. 3 is a diagram showing an example of control when the exposure time of the photodetector 17a coincides with the time it takes for the aperture plate 12 to move a distance obtained by multiplying the array period Δd by 1. Fig. 4 is a diagram showing an example of control when the exposure time of the photodetector 17a coincides with the time it takes for the aperture plate 12 to move a distance obtained by multiplying the array period Δd by n (for example, n=2).

[0028] The left side of Figure 3 shows an imaging target area 27 that exists at a predetermined position relative to the partial area W shown in the upper part of Figure 2. If the exposure time of the photodetector 17a is controlled so as to coincide with the time it takes for the aperture plate 12 to move a distance obtained by multiplying the array period Δd by 1 (m=1) from the state shown on the left side of Figure 3, the state will be as shown on the right side of Figure 3. In this control case, the range A through which the center of one pixel passed during exposure is shown.

[0029] The left side of Fig. 4, like the left side of Fig. 3, shows an imaging target area 27 that exists at a predetermined position relative to a partial area W. If the exposure time of the photodetector 17a is controlled so as to coincide with the time it takes for the aperture plate 12 to move a distance obtained by multiplying the array period Δd by 2 (n=2) from the state shown on the left side of Fig. 4, the state shown on the right side of Fig. 4 results. In this control case, the range B through which the center of one pixel passes during exposure is shown.

[0030] Scanning multiple periods n times to acquire one image can reduce measurement errors due to deviations in measurement timing and individual differences in the diameter of opening 25. Scanning multiple periods can be achieved by one of the following control methods. (1) The scanning speed (i.e., the movement speed of the aperture plate 12) is not changed, and the exposure time is increased by n times to perform measurement. (2) Measure by increasing the scan speed by n times without changing the exposure time.

[0031] As a result, n times as many apertures 25 pass through a pixel, and the actual measurement timing is the average of n scans. As a result, the measurement timing difference in the acquired image is 1 / n compared to one cycle scan. Furthermore, since n times as many apertures 25 are passed by moving the aperture plate 12, it is also possible to smooth out manufacturing errors of the apertures 25 at the same time. Furthermore, although the scan time increases, manufacturing errors of the apertures 25 may be smoothed out by not only multiple cycle scans but also by multiplying the exposure time by n times.

[0032] Fig. 5 is a diagram for explaining the amount of deviation in measurement timing between one-cycle scanning and two-cycle scanning, taking the case of (2) of the above control methods (1) and (2) as an example.

[0033] In one-cycle scanning, light passes through a first pixel at the timing (black circle) when exposure starts, and as the aperture plate 12 moves, light passes through a second pixel adjacent to the first pixel at the timing (white circle) just before the timing when exposure ends. On the other hand, in two-cycle scanning, light passes through a first pixel at the timing (black circle) when exposure starts, and as the aperture plate 12 moves, light passes through the first pixel at the next timing (black circle). In two-cycle scanning, light passes through a second pixel adjacent to the first pixel at the timing (white circle) just before the timing (black circle) when light passes through the first pixel, and as the aperture plate 12 moves, light passes through the second pixel adjacent to that at the timing (white circle) just before the timing when exposure ends.

[0034] In the above case, the deviation in measurement timing during two-cycle scanning is 1 / 2 (1 / n in the case of n) of the deviation in measurement timing during one-cycle scanning. Reducing the deviation in measurement timing reduces the difference in height of the object 15 to be measured, thereby reducing measurement errors of the aperture 25. On the other hand, in the case of two-cycle scanning using the control method (2) above, the movement speed of the aperture plate 12 is doubled, so approximately the same exposure time is sufficient.

[0035] Note that switching between one cycle scan and multiple cycle scan is possible under control of the imaging control unit 541, which will be described later. For example, based on an instruction input by the operator via the input unit 51, the imaging control unit 541 can switch between one cycle scan and multiple cycle scan by the control method (1), switch between one cycle scan and multiple cycle scan by the control method (2), switch between one cycle scan, multiple cycle scan by the control method (1) and multiple cycle scan by the control method (2), or switch between multiple cycle scan by the control method (1) and multiple cycle scan by the control method (2).

[0036] FIG. 6 is a perspective view showing an example of the configuration of the focal position changing unit 14. As shown in FIG.

[0037] When a parallel-plate transparent member 31 is placed in the optical path of the objective lens 13, the position of the object-side focusing surface of the objective lens 13 moves in the Z direction. The amount of this movement can be controlled by the refractive index and thickness of the transparent member 31.

[0038] 6, transparent members 31 with different movement widths are arranged at equal intervals along the rotation direction of a rotating body 32. By continuously rotating this rotating body 32 at a predetermined speed by a driving unit 33 such as a motor, the position of the object-side focusing surface of the objective lens 13 can be moved discretely (stepwise) in the Z direction each time each transparent member 31 intersects with the optical axis of the objective lens 13.

[0039] The rotation state of the rotor 32 is detected by a timing sensor 34. The output of the timing sensor 34 is provided to the image processing device 20. The image processing device 20 stores information in advance that associates each transparent member 31 with the Z-axis coordinate of the object-side focusing point. The image processing device 20 repeatedly exposes the photodetector group 17 at the timing when each transparent member 31 intersects with the optical axis based on the output of the timing sensor 34, thereby enabling easy and high-speed imaging at each of the multiple discrete object-side focusing point positions.

[0040] The driving unit 33 may be configured to be controllable by the image processing device 20. In this case, the image processing device 20 can control the rotation speed of the rotating body 32.

[0041] Of the light reflected by the object 15, the light reflected at the object-side focusing point is focused at a point (hereinafter referred to as the image-side focusing point) that is optically conjugate with the object-side focusing point by the objective lens 13. There is a one-to-one correspondence between the aperture 25 as a point light source and the object-side focusing point.

[0042] In this embodiment, an example will be described in which the image-side focusing point coincides with the aperture 25 serving as a point light source. In this case, light that has passed through aperture 25 is focused at the object-side focusing point, and is reflected at this object-side focusing point to re-enter aperture 25.

[0043] The light that re-enters aperture 25 is deflected by polarizing beam splitter 24 and enters imaging optical system 35, and then enters photodetector 17a that constitutes photodetector group 17. Here, imaging optical system 35 is configured to form an image of aperture 25 on the photoelectric conversion surface of photodetector group 17. Aperture 25 (image-side focusing point) and photodetector 17a, which is disposed at a position corresponding to aperture 25, are in a conjugate relationship with each other due to polarizing beam splitter 24 and imaging optical system 35.

[0044] The photodetector group 17 is a so-called two-dimensional image sensor, and photodetectors 17a constituting the photodetector group 17 are configured by CCD (Charge Coupled Device) image sensors or CMOS (Complementary Metal Oxide Semiconductor) image sensors, and output signals according to the intensity of the irradiated light to the image processing device 20. Furthermore, the photodetector group 17 has its light detection timing controlled by the image processing device 20.

[0045] The image processing device 20 can use the signals received from the photodetector group 17 as image data (hereinafter referred to as confocal image data) for generating an image (hereinafter referred to as a confocal image). Furthermore, the image processing device 20 may generate a confocal image based on the confocal image data for each exposure, for example. In this embodiment, an example will be described in which the image processing device 20 generates a confocal image for each exposure of the photodetector group 17. Note that as long as the image processing device 20 can obtain the output signals of the photodetector group 17 for each exposure, it is possible to perform three-dimensional shape measurement based on these output signals, and it is not necessary to generate a confocal image.

[0046] The stage XY displacement unit 22 of the stage driver 18 displaces the stage 16 in a direction perpendicular to the optical axis direction. For example, the stage XY displacement unit 22 is used to move the measurement target area within the XY plane between measurements.

[0047] This stage XY displacement unit 22 has an X-axis displacement mechanism 41 and a Y-axis displacement mechanism 42 that position the stage 16 in the X-axis and Y-axis directions. The X-axis displacement mechanism 41 and the Y-axis displacement mechanism 42 are configured by, for example, servo motors, and the amount, direction, and timing of displacement are controlled by the image processing device 20 via an XY-axis driver 45.

[0048] 7 is a block diagram showing an example of the internal configuration of the image processing device 20. The image processing device 20 can be configured, for example, by a desktop or notebook personal computer. The image processing device 20 has an input unit 51, a display unit 52, a storage unit 53, and a control circuit 54.

[0049] The input unit 51 includes an input device that can be operated by an operator and an input circuit that inputs signals from the input device. The input device can be realized by a trackball, a switch, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a touchscreen that combines a display screen and a touchpad, a non-contact input device that uses an optical sensor, a voice input device, etc. When the operator operates the input device, the input circuit generates a signal corresponding to the operation and outputs it to the control circuit 54.

[0050] The display unit 52 is configured by a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display, and displays various information under the control of the control circuit 54.

[0051] The storage unit 53 includes a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, etc. The storage unit 53 may also include a portable medium such as a USB (Universal Serial Bus) memory or a DVD (Digital Video Disk). The storage unit 53 stores various processing programs (including application programs and an OS (Operating System)) used in the control circuit 54 and data required for executing the programs. The OS may also include a GUI (Graphical User Interface) that makes extensive use of graphics to display information to the operator on the display unit 52 and allows basic operations to be performed using the input unit 51. The storage unit 53 previously stores information associating each parallel-plate-shaped transparent member 31 with the Z-axis coordinate of the object-side focal point.

[0052] The control circuit 54 is configured with a CPU, a storage medium including RAM and ROM, etc. The control circuit 54 loads the linear scanning program stored in the storage unit 53 and data required for executing this program into the RAM, and executes a process of linearly scanning the surface of the object to be measured in accordance with this program.

[0053] The storage unit 53 may be configured so that some or all of the programs and data are downloaded via an electronic network. Here, the electronic network refers to any information and communication network that utilizes electrical communication technology, and includes wireless / wired LANs (Local Area Networks) and the Internet, as well as telephone communication networks, optical fiber communication networks, cable communication networks, and satellite communication networks.

[0054] The control circuit 54 functions as at least an imaging control unit 541, a height determination unit 542, and an image generation unit 543 according to a linear scanning program. Each of these units 541 to 543 uses a required work area of ​​the RAM as a temporary storage location for data. Each of the units 541 to 543 may be configured by hardware logic such as an ASIC (Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0055] The imaging control unit 541 controls the focal position changing unit 14, the photodetector group 17, and the aperture plate displacement unit 26, thereby causing the photodetector group 17 to perform exposure (image capture) for each period in which the imaging target region 27 is included in the parallel plate-shaped transparent member 31 during a period in which the aperture plate 12 is displaced at a uniform speed in the Y-axis direction by the aperture plate displacement unit 26. At this time, the imaging control unit 541 controls the movement speed of the aperture plate 12, the rotation speed of the rotor 32, and the exposure time and exposure timing of the photodetector group 17 so that the exposure time of the photodetector group 17 matches the time it takes for the aperture plate 12 to move a distance obtained by multiplying the array period Δd by n (n is an integer of 2 or more).

[0056] The height determination unit 542 acquires the Z-axis coordinate of the current object-side focal point (information on the transparent member 31 that currently intersects with the optical axis) from the imaging control unit 541 and also acquires the output of the photodetector group 17, and calculates the position in the optical axis direction of the measured object 15 at which the intensity of the reflected light incident on the photodetector 17a is maximum for each photodetector 17a based on the signals from the photodetectors 17a for each position of the object-side focal point that has been discretely changed in the optical axis direction.

[0057] Here, for example, if we consider a coordinate system (stage coordinate system) with the center of stage 16 as the origin, the X and Y coordinates of the measurement target area (image capture target area 27) in this stage coordinate system can be uniquely determined from the current position of stage XY displacement unit 22. Therefore, the X and Y coordinates in the stage coordinate system corresponding to each photodetector 17a are uniquely determined according to the current position of stage XY displacement unit 22.

[0058] In shape measurement technology using a confocal optical system, various methods have been known in the past to calculate the Z-axis coordinate of the measured object 15 at which the intensity of the reflected light is at its maximum based on the intensities of multiple signals discretely acquired from the output of the photodetector 17a, and any of these can be used.

[0059] The image generation unit 543 generates a shape image of the measured object 15 based on the position of the measured object 15 in the optical axis direction for each photodetector 17a calculated by the height determination unit 542, and displays this shape image on the display unit 52.

[0060] The number of object-side focal point positions (optical axis direction measurement positions) that are discretely changed in the optical axis direction and that are required for one measurement (processing to generate one shape image) may be set to 1 / 2 or 1 / 3 (e.g., 1 / 2 or 1 / 3) of the number of transparent members 31 of the rotating body 32 divided by a positive integer. For example, if the number of optical axis direction measurement positions matches the number of transparent members 31 of the rotating body 32, one measurement can be performed when the rotating body 32 rotates once. The number of periods of the openings 25 provided in the aperture plate 12 should be set to a number that allows at least one measurement to be performed while the aperture plate 12 moves at a constant speed in a predetermined direction (either the positive or negative direction) in the Y-axis direction.

[0061] Furthermore, at least one measurement may be performed while the aperture plate 12 is moving at a constant speed in a predetermined direction in the Y-axis direction (either the positive or negative direction), and the next measurement may be performed after the direction of movement of the aperture plate 12 is reversed and the aperture plate 12 returns to a constant speed state. In this case, the object to be measured 15 may be moved in the XY direction to change the measurement target area during the period when the aperture plate 12 is accelerating or decelerating due to the reversal of the direction of movement of the aperture plate 12. In this case, the total time required for multiple measurements can be shortened.

[0062] Since the main purpose of a confocal "microscope" is observation, continuous imaging is required. In this regard, a confocal microscope using a Nipkow disk is convenient because confocal images can be obtained without interruption as long as the Nipkow disk is rotating. However, in surface shape measurement, there is a limit to one measurement (one field of view), so continuous imaging is not essential. Even if a scan with an end point, such as the method using the movement of the aperture plate 12 according to this embodiment, is used instead of an endless scan such as the rotation of a Nipkow disk, there is no problem as long as one measurement is completed while the aperture plate 12 is moving at a constant speed.

[0063] The three-dimensional shape measurement apparatus 10 according to this embodiment is capable of linearly scanning the aperture plate 12. Therefore, by linearly scanning the aperture plate 12 while exposing the photodetector group 17, one aperture 25 can correspond to multiple pixels, thereby achieving high resolution. Furthermore, the scanning trajectory of the object-side focusing point can be made strictly linear, and the scanning area (measurement target area) on the surface of the measurement object 15 can be made rectangular, thereby improving compatibility with two-dimensional image sensors compared to when a Nipkow disk is used.

[0064] In this embodiment, an example has been shown in which the aperture plate 12 is a pinhole array type having a plurality of apertures 25, but it may also be a slit array type, for example, as long as the apertures have a predetermined arrangement period Δd. When the aperture plate 12 is a slit array type, if a plurality of slits having long sides in a direction perpendicular to the movement direction of the aperture plate 12 are arranged in a row so that the slit center-to-center spacing in the movement direction is 1 / (Δd) a positive integer, the predetermined arrangement period can be treated as Δd.

[0065] When using an aperture plate 12 with such slits, the minimum scan width required to obtain a confocal image is equal to the slit center distance (pitch) Δd. In other words, if the aperture plate 12 is moved by the slit pitch, confocal data can be obtained by all of the photodetectors 17a that make up the photodetector group 17. Therefore, when using a slit array type aperture plate 12, it is possible to reduce the movement distance of the aperture plate 12 required to obtain one confocal image compared to when using a pinhole array type aperture plate 12.

[0066] Next, the detailed structure of the aperture plate 12 and a dustproof method for the aperture plate 12 will be described.

[0067] The apertures 25 are provided in the aperture plate 12 and have a diameter of 1 to several μm. For this reason, it is preferable that at least the area of ​​the aperture plate 12 where the plurality of apertures 25 are provided (hereinafter referred to as the aperture area) be provided with dustproofing measures. When a method of sealing the entire optical system of the three-dimensional shape measurement device 10 in a housing or a method of sealing the aperture plate 12 and the aperture plate displacement unit 26 in a housing are adopted as a dustproofing method for the aperture area, both of these methods are large-scale and involve the possibility of dust being generated by the driving units such as the aperture plate displacement unit 26 and adhering to the aperture array area.

[0068] Therefore, the three-dimensional shape measuring apparatus 10 according to this embodiment is provided with a cover member 60 for protecting the aperture plate 12 from dust. The cover member 60 is used to protect the aperture area of ​​the aperture plate 12 from dust from both sides. FIG. 1 shows a schematic diagram of an example of the configuration of the cover member 60. FIG. 8(a) is a side view of the aperture plate 12 provided with the cover member 60 according to the example shown in FIG. 1, and FIG. 8(b) is a perspective view thereof.

[0069] The configuration example of the cover member 60 shown in FIGS. 1 and 8 is suitable for the case where the aperture plate 12 is made of a transparent substrate 12a, and the side surface of this transparent substrate 12a facing the light source is chrome-etched to form the aperture 25. In this case, the side surface of the aperture region facing the objective lens is dustproofed by the transparent substrate 12a. Therefore, the cover member 60 only needs to protect the side surface of the aperture region facing the light source from dust. Therefore, as shown in FIGS. 1 and 8, the cover member 60 only needs to be detachably provided on the light source side of the aperture plate 12 (the side surface on which the aperture 25 is formed) so as to cover the aperture 25, and protect the side surface of the aperture region facing the light source from dust. Details of the configuration of the aperture plate 12 and the cover member 60 in this case will be further described below.

[0070] The cover member 60 has a transparent body 61, a support member 62 for the transparent body 61, and an intermediate plate 63. On the other hand, the aperture plate 12 has an aperture region in which a plurality of apertures 25 are formed on the side surface of the transparent substrate 12a facing the light source.

[0071] The support member 62 and the intermediate plate 63 are provided with an opening for transmitting light from the light source 11a. The transparent body 61 is adhered to the entire periphery of the opening of the support member 62, either inside or outside. The support member 62 is screwed to the intermediate plate 63 so that the center of the opening of the support member 62 and the center of the opening of the intermediate plate 63 are approximately aligned. Note that if a packing 64 such as an O-ring is placed on the contact surface between the support member 62 and the intermediate plate 63 so as to surround the opening of the intermediate plate 63, the dustproof effect can be further improved.

[0072] Furthermore, the aperture plate 12 is adhered to the entire periphery of the side surface of the intermediate plate 63 opposite to the side to which the support member 62 is fixed, so that the formation surface 65 of the apertures 25 faces the apertures of the intermediate plate 63. As a result, an aperture region in which a plurality of apertures 25 are formed can be contained within the sealed space formed by the aperture plate 12, transparent body 61, support member 62, and intermediate plate 63. Furthermore, the aperture plate 12 and cover member 60 are displaced integrally in the Y-axis direction by the aperture plate displacement portion 26.

[0073] The aperture plate 12 does not have to be bonded to the intermediate plate 63 all around, and may be screwed via a packing such as an O-ring so that it can be attached and detached to the intermediate plate 63. In this case, the cover member 60 can be attached and detached to the aperture plate 12. When the aperture plate 12 is pressure-attached to the cover member 60 so that it can be attached and detached, replacement and maintenance of the aperture plate 12 can be easily performed.

[0074] The intermediate plate 63 is screwed to the vertical portion of the L-shaped jig 66 so that the aperture plate 12 fits into the opening of the L-shaped jig 66. The horizontal portion of the L-shaped jig 66 is screwed to an aperture plate mounting portion 67. The aperture plate mounting portion 67 is displaced in the Y-axis direction along a linear guide 68a by a linear motor 68 via an imaging control portion 541. Drive control by the linear motor 68 is performed using output signals from a group of various sensors 69 provided near the linear guide 68a. The group of sensors 69 includes an origin sensor, a limit sensor, etc.

[0075] The cover member 60 is provided on the formation surface 65 of the opening 25 on the light source side of the aperture plate 12 so as to cover the aperture region, thereby protecting the light source side of the aperture region from dust. Therefore, compared to covering the entire aperture plate displacement unit 26 or covering the entire optical system of the three-dimensional shape measurement device 10, dust can be prevented with an extremely light and simple configuration, and adverse effects caused by dust generation from the motor can be prevented in advance.

[0076] The transparent body 61 or the transparent substrate 12a has the function of preventing dust from adhering to the opening area of ​​the aperture plate 12, but cannot prevent dust from adhering to the transparent body 61 or the transparent substrate 12a itself. However, if the thickness of the transparent body 61 or the transparent substrate 12a is sufficiently thick, dust adhering to the surface of the transparent body 61 or the transparent substrate 12a will be away from the position of the aperture plate 12, which is the imaging position of the imaging optical system 35 or the objective lens 13, and since the imaging light beam is at a thick position, it will not completely block the imaging light beam, and therefore the impact on measurement will be small.

[0077] However, inserting a thick transparent body 61 into the optical path has a significant effect on the imaging performance of the imaging optical system 35. Therefore, the imaging optical system 35 must be designed taking into consideration the thickness of this transparent body 61. Of course, the transparent body 61 must be made of optical glass that is free of striae and has sufficiently high surface precision and parallelism.

[0078] 1 and 8 show an example in which the opening 25 is formed on the light source side of the transparent substrate 12a and the cover member 60 protects the light source side of the opening region from dust, but the aperture plate 12 and the cover member 60 may be arranged inverted as a whole on the optical path. That is, the opening 25 may be formed on the objective lens side of the transparent substrate 12a and the cover member 60 protects the objective lens side of the opening region from dust.

[0079] Furthermore, the cover member 60 need only have a configuration necessary to protect the opening area of ​​the aperture plate 12 from dust from both sides, and is not limited to the configuration shown in FIGS. 1 and 8. In the configuration example shown in FIGS. 1 and 8, one side of the opening area of ​​the aperture plate 12 is protected from dust by the transparent substrate 12a, so the cover member 60 need only be configured to protect the other side of the opening area from dust. On the other hand, if the aperture plate 12 is made of a plate with high light-blocking properties (including a metal plate and a plastic plate coated with a light-blocking paint) and the opening 25 is formed by providing a hole in this plate, the cover member 60 may be configured to cover the opening area of ​​the aperture plate 12 from both the light source side and the objective lens side. In this case, for example, the cover member 60 may have two pairs of transparent bodies 61 and support members 62 shown in FIG. 1, and each pair may be detachably attached to the light source side and the objective lens side of the opening area of ​​the aperture plate 12 made of a plate with high light-blocking properties.

[0080] Next, an imaging control method by the imaging control unit 541 will be described.

[0081] The imaging control unit 541 controls the focus position changing unit 14, the photodetector group 17 and the aperture plate displacement unit 26 to control the movement speed of the aperture plate 12, the rotation speed of the rotating body 32 and the exposure time and exposure timing of the photodetector group 17 so that the exposure time of the photodetector group 17 coincides with the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by n (n is an integer greater than or equal to 2).

[0082] For example, in the case of control to match the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by 1 (shown in FIG. 3), the array period Δd of the openings 25 is 100 μm, the speed v of the constant movement of the aperture plate 12 is 10 mm / s, and the time Δt required to move the array period Δd is 10 ms. In the case of control to match the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by n (shown in FIG. 4), when the control method (1) is employed, the speed v of the constant movement of the aperture plate 12 remains 10 mm / s, and the time Δt required to move the distance equal to the array period Δd multiplied by n is set to (10 × n) ms. In this control method (1), the exposure time Δt1 of the photodetector group 17 is controlled to exactly match the time equal to Δt = 10 ms multiplied by n. Alternatively, in the case of control so that the time it takes for the aperture plate 12 to move a distance equal to the array period Δd multiplied by n (shown in FIG. 4), when the above control method (2) is employed, the speed v of the constant movement of the aperture plate 12 is set to (10×n) mm / s while the time Δt required to move a distance equal to the array period Δd multiplied by n is kept at 10 ms. In the case of this control method (2), the exposure time Δt1 of the photodetector group 17 is controlled to accurately coincide with the time Δt = 10 ms. When the above control method (2) is employed, if the apertures 25 have a diameter of 1 to several μm, it is preferable that n is 2 to 4, that is, the speed v of the constant movement of the aperture plate 12 is approximately 20 to 40 mm / s.

[0083] However, even if the exposure time Δt1 exactly matches Δt·n (the above control method (1)) or Δt (the above control method (2)), if there is a slight error in the exposure time Δt1, a pattern will appear in the image. The pattern is determined by the position of the opening 25 at the start of exposure. In other words, underexposure or overexposure occurs in pixels near the position of the opening 25 at the start of exposure, and this appears as a pattern. In addition, if the arrangement direction of the openings 25 and the movement direction of the aperture plate 12 do not exactly match and are tilted from each other, a similar pattern will appear even if the tilt is slight. These patterns are also determined by the position of the opening 25 at the start of exposure. Therefore, if the position of the opening 25 at the start of exposure is random, the pattern will also fluctuate randomly.

[0084] On the other hand, the exposure start timing is determined according to the trigger timing of the timing sensor 34 of the focus position changing unit 14. For this reason, if the rotation speed of the rotor 32 is determined completely independently of the aperture plate displacement unit 26, for example, the above pattern will vary almost randomly for each captured image, and this will be reflected as a noise component in the axial response curve used in measurement calculations, resulting in a decrease in measurement accuracy.

[0085] To avoid this, exposure can be prohibited from starting at random timing, and exposure can be started only at intervals that are multiples of the time it takes for the aperture plate 12 to move by the n-arrangement period Δd·n (in the above example, (10 × n) ms or 10 ms). This prevents random generation of patterns and allows for a clearer image.

[0086] Fig. 9 is an explanatory diagram showing an example of a timing chart for obtaining a clear image. Fig. 9 explains the case of (1) of the above control methods (1) and (2) as an example. In the case of the above control method (2), Δt·n in Fig. 9 can be read as Δt.

[0087] 9, the imaging control unit 541 exposes the photodetector group 17 every time the transparent member 31 of the rotating body 32 intersects with the optical axis. At this time, the imaging control unit 541 matches the exposure time Δt1 of the photodetector group 17 to only the time Δt·n required for movement through n (n is an integer equal to or greater than 2) array periods Δd·n. At this time, the imaging control unit 541 controls the movement speed v of the aperture plate 12 so that v = Δd / Δt. In addition, the imaging control unit 541 matches the interval between the start times of adjacent exposures to the time Δt·k obtained by multiplying Δt by an integer k greater than n.

[0088] Next, a method for reducing the influence of the force generated as the aperture plate 12 accelerates or decelerates will be described.

[0089] It is preferable that the aperture plate 12 be accelerated to a constant velocity as quickly as possible. However, if strong acceleration or deceleration is performed, the force generated by the acceleration or deceleration may cause vibration, which may reduce accuracy. In order to reduce the effect of such force generated by acceleration or deceleration, it is recommended to provide a reaction force mechanism.

[0090] 10 is a perspective view showing one configuration example of the reaction force mechanism 70. The reaction force mechanism 70 has a moving body 71 that is displaced in the Y-axis direction along a linear guide 68a by a linear motor 68, and an adjustment member 72 that is provided on the moving body 71 and displaces integrally with the moving body 71.

[0091] The movable body 71 is driven by the linear motor 68 via the imaging control unit 541 so as to reduce (cancel) the influence of the force generated by the acceleration and deceleration of the aperture plate 12. For example, if the weight of the adjustment member 72 is selected so that the weight of the object placed on the aperture plate placing unit 67 including the aperture plate placing unit 67 matches the weight of the reaction force mechanism 70, the centers of gravity of these are located midway between the aperture plate placing unit 67 and the movable body 71. In this case, the movable body 71 can be accelerated and decelerated symmetrically with respect to the center of gravity of the aperture plate placing unit 67 in opposite directions with the same magnitude, thereby reducing the influence of the force generated by the acceleration and deceleration of the aperture plate 12.

[0092] (Second embodiment) Next, a second embodiment of the three-dimensional shape measuring apparatus according to the present invention will be described.

[0093] FIG. 11 is a schematic overall view showing an example of the configuration of a three-dimensional shape measuring apparatus 10A according to the second embodiment of the present invention.

[0094] The three-dimensional shape measuring device 10A shown in this second embodiment differs from the three-dimensional shape measuring device 10 shown in the first embodiment in that a focal position changing unit 14 is provided on the aperture plate 12 side of the objective lens 13. Since the other configurations and operations are substantially the same as those of the three-dimensional shape measuring device 10 shown in Fig. 1, the same configurations are given the same reference numerals and descriptions thereof will be omitted.

[0095] Microscopes are highly versatile because they allow you to select the optimum magnification depending on your purpose; for example, by changing the objective lens, you can increase the magnification (observation) accuracy, or conversely, you can observe the entire object with a wide field of view, but with less accuracy.

[0096] Although it is desirable for the measurement to have similar versatility, such versatility cannot be obtained when the focal position changing unit 14 including the rotor 32 is inserted on the side of the object to be measured 15 (between the object to be measured 15 and the objective lens 13) as in the three-dimensional shape measurement device 10 according to the first embodiment. This is because the thickness pitch of the transparent member 31 on the rotor 32 is determined so that three or more values ​​can be sampled within the central peak of the confocal axial response curve (the curve of the detector change when moved in the Z direction), whereas replacing the objective lens 13 means that the NA (numerical aperture) of the objective lens 13 on the object to be measured 15 side changes.

[0097] The width of the central peak is determined by the NA of the measured object 15. Therefore, when the objective lens 13 is replaced, the pitch of the transparent member 31 of the rotor 32 must also be changed. In other words, it becomes necessary to replace not only the objective lens 13 but also the rotor 32 itself.

[0098] Therefore, when the rotor 32 is located in the image-side space (aperture plate 12 side) as shown in FIG. 11, the sampling pitch in the image-side space, determined by the thickness pitch of the transparent member 31, is inversely proportional to the lens longitudinal magnification (the square of the lateral magnification) in the space on the measurement object 15 side. Therefore, even if the objective lens 13 is replaced to change the magnification, not only the width of the central peak but also the sampling pitch on the measurement object 15 side automatically changes inversely proportional to the square of the lateral magnification. Therefore, when the rotor 32 is located in the image-side space (aperture plate 12 side) as shown in FIG. 11, there is no need to replace the rotor 32 even if the objective lens 13 is replaced. Of course, the object space in the optical axis direction that can actually be measured (Z measurement range) also changes inversely proportional to the square of the lateral magnification, but this is reasonable because higher magnifications typically result in smaller objects being observed.

[0099] Therefore, the three-dimensional shape measuring apparatus 10A according to the second embodiment makes it easy to change the magnification of the objective lens 13. Furthermore, compared to when the focal position changing unit 14 is provided on the side of the object 15 to be measured, the working distance in the space on the side of the object 15 to be measured can be sufficiently secured, improving workability and making it easy to provide additional lighting such as oblique incidence lighting.

[0100] According to the control methods (1) and (2) of the three-dimensional shape measurement apparatus 10, 10A of the present invention, measurement errors can be reduced in pinhole array scanning using a confocal optical system, thereby enabling accurate measurement. Specifically, according to the control methods (1) and (2), deterioration of scanning uniformity due to vibrations and the like can be reduced, and accurate measurement can be achieved regardless of individual differences in the diameter of the opening 25. In particular, according to the control method (2), the above-mentioned effects can be achieved without extending the exposure time. Although the type of the measurement object 15 is not particularly limited, in the case of the control method (2), it is preferable to narrow the measurement range, and therefore it is preferable that the measurement object 15 be a semiconductor chip or a protruding connection electrode (bump) formed on a wiring lead.

[0101] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

[0102] For example, the focal position changing unit 14 is not limited to the configuration shown in FIG. 6 as long as it can move the position of the object-side focal point of the objective lens 13 in the Z direction. For example, it may be configured with an optical path length adjustment member made of a transparent body having a predetermined refractive index, the transparent body having a variable thickness in the optical axis direction, and an adjustment member drive unit that changes the thickness of the transparent body. In this case, the focal position changing unit 14 can change the position of the object-side focal point in the optical axis direction by changing the thickness of the transparent body in the optical axis direction where it intersects with the optical axis, thereby changing the optical path length of the light passing through the optical path length adjustment member. The optical path length adjustment member can be configured, for example, with two parallel flat glass plates arranged parallel to each other and a liquid filled between them. In this case, the adjustment member drive unit can change the optical path length by changing the volume of the liquid. [Explanation of symbols]

[0103] 10, 10A Three-dimensional shape measurement device 11 Illumination optical system 11a light source 12 Aperture plate 13 Objective Lens 14 Focus position change unit 15 Measurement object 16 Loading platform 17 Photodetector group 18 Stage drive unit 20 Image processing device 21 Z displacement part of stage 22 Stage XY displacement section 25 Opening 26 Aperture plate displacement section 27 Imaging target area 31 Transparent parts 32 Rotating body 34 Timing sensor 35 Imaging optical system 541 Imaging control unit 542 Height determination unit 60 Cover member 61 Transparent body 62 Support member 63 Intermediate plate 64 Gasket 67 Opening plate placement part 68 Linear Motor 70 Reaction mechanism

Claims

1. A three-dimensional shape measurement device using a confocal optical system, an aperture plate having a flat transparent substrate, the aperture plate having a plurality of confocal apertures, which transmit light from a light source, two-dimensionally arranged at a predetermined array period on one surface of the transparent substrate; an objective lens that focuses each of the light beams that have passed through the plurality of confocal apertures at an object-side focusing point and that refocuses the focused light beams that are reflected by the object to be measured at the corresponding confocal apertures; a rotating body in which a plurality of parallel plate-shaped members, each having at least one of a refractive index and a thickness different from one another, are arranged along a rotation direction so as to intersect with the optical axis of the objective lens; a driving unit that continuously rotates the rotating body at a predetermined speed; and a focal position changing unit that discretely changes the position of the object-side light-focusing point in the optical axis direction each time the parallel plate-shaped members intersecting with the optical axis change with the rotation of the rotating body; a photodetector group including a plurality of photodetectors that output signals according to the intensity of the reflected light that has passed through the confocal aperture again; an aperture plate displacement unit that displaces the aperture plate at a uniform speed in a predetermined direction perpendicular to the optical axis direction so as to change the relative positional relationship between the position of the object-side focusing point and the position of the object to be measured in the direction perpendicular to the optical axis direction; an imaging control unit that causes the group of photodetectors to perform multiple exposures during a period in which the aperture plate is displaced at a uniform speed in the predetermined direction perpendicular to the optical axis direction by the aperture plate displacement unit, causes the group of photodetectors to perform each exposure for each period in which an imaging target area is included in the parallel plate-shaped member, and controls the moving speed of the aperture plate, the rotation speed of the rotor, and the exposure time and exposure timing of the group of photodetectors so that the exposure time of the group of photodetectors coincides with the time it takes for the aperture plate to move a distance obtained by multiplying the predetermined arrangement period by an integer n of 2 or more; a height determination unit that estimates, for each photodetector, a position in the optical axis direction of the measured object at which the intensity of the reflected light incident on the photodetector is maximized, based on a signal from the photodetector for each position of the object-side focusing point that is discretely changed in the optical axis direction; a cover member provided on the one surface of the transparent substrate of the aperture plate and displaced integrally with the aperture plate by the aperture plate displacement portion, the cover member including: a transparent body that transmits light from the light source and irradiates the light onto the plurality of confocal apertures; and a support body that supports the entire periphery of the transparent body and is provided on the one surface of the transparent substrate of the aperture plate so as to surround the plurality of confocal apertures; an imaging optical system that is designed in consideration of the optical characteristics of the entire optical system including the transparent body of the cover member, and that guides the reflected light that has passed through the confocal aperture again to the photodetector; Equipped with The cover member is the transparent body is provided on the one surface of the aperture plate via the support member so that the plurality of confocal apertures are positioned apart from the transparent body within an enclosed space formed by the transparent body and the support member of the cover member and the transparent substrate of the aperture plate, and the transparent body is positioned between the light source and the aperture plate; Three-dimensional shape measurement device.

2. 2. The three-dimensional shape measurement device of claim 1, wherein the imaging control unit switches between control in which the exposure time of the photodetector group coincides with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by an integer n of 2 or greater, and control in which the exposure time of the photodetector group coincides with the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by 1.

3. 3. The three-dimensional shape measurement device of claim 2, wherein the imaging control unit matches the exposure time in control such that the exposure time of the photodetector group matches the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by an integer n of 2 or greater, with the exposure time in control such that the exposure time of the photodetector group matches the time it takes for the aperture plate to move a distance equal to the predetermined array period multiplied by 1.

4. The three-dimensional shape measuring apparatus according to claim 1 , wherein the cover member is detachable from the aperture plate.

5. The imaging control unit further controlling the movement speed of the aperture plate, the rotation speed of the rotor, and the exposure time and exposure timing of the photodetector group so that a period from the start time of any one of the plurality of exposures to the start time of the next exposure coincides with a time taken for the aperture plate to move a distance obtained by multiplying the predetermined array period by an integer k greater than the integer n of 2 or more; 4. The three-dimensional shape measuring apparatus according to claim 1.

6. The focus position changing unit the plurality of parallel plate-shaped members are disposed between the aperture plate and the objective lens so as to intersect with an optical axis of the objective lens on the aperture plate side; 4. The three-dimensional shape measuring apparatus according to claim 1.

7. a stage on which the object to be measured is placed; a stage displacement unit that displaces the stage in a direction perpendicular to the optical axis direction so as to change the relative positional relationship between the position of the object-side focusing point and the position of the object to be measured in the direction perpendicular to the optical axis direction; Furthermore, The stage displacement unit is changing a relative positional relationship between the position of the object-side focusing point and the position of the object to be measured in a direction perpendicular to the optical axis direction during a period excluding a period during which the aperture plate is displaced at a uniform speed in the predetermined direction perpendicular to the optical axis direction; A period excluding a period in which the aperture plate is displaced at a constant speed in the predetermined direction perpendicular to the optical axis direction is a period during which the aperture plate is accelerated and decelerated in the predetermined direction by the aperture plate displacement unit, and a time or period during which the movement direction of the aperture plate is reversed within the predetermined direction by the aperture plate displacement unit, 4. The three-dimensional shape measuring apparatus according to claim 1.

8. The aperture plate displacement unit is an aperture plate placement portion on which the aperture plate is placed; a linear motor controlled by the imaging control unit to displace the aperture plate mounting portion in the predetermined direction perpendicular to the optical axis direction; 4. The three-dimensional shape measuring apparatus according to claim 1, further comprising:

9. The aperture plate displacement unit is a reaction force mechanism that is displaced in the predetermined direction perpendicular to the optical axis direction; Furthermore, The imaging control unit operating the reaction force mechanism so as to reduce the effect of a force generated by acceleration / deceleration of the aperture plate mounting portion caused by the linear motor; The three-dimensional shape measuring apparatus according to claim 8.

10. The focal position changing unit, instead of the rotating body and the driving unit, an optical path length adjusting member provided at a position intersecting the optical axis of the objective lens, the optical path length adjusting member being made of a transparent member having a predetermined refractive index, and the thickness of the transparent member in the optical axis direction being variable; an adjustment member drive unit for changing the thickness of the transparent member in the optical axis direction; the position of the object-side light-focusing point is changed in the optical axis direction by changing the thickness of the transparent member intersecting the optical axis in the optical axis direction to change the optical path length, 4. The three-dimensional shape measuring apparatus according to claim 1.

Images